Conventionally, electronic devices, such as a digital camera and a portable terminal with camera function, include a camera module with a solid-state imaging device. The solid-state imaging device includes a plurality of photoelectric conversion elements. The plurality of photoelectric conversion elements is two-dimensionally arranged in a matrix pattern corresponding to respective pixels of a captured image. Each photoelectric conversion element photoelectrically converts incident light into electric charge of an amount corresponding to an amount of received light and accumulates the electric charges as signal electric charges indicating luminance of each pixel.
Between each of the photoelectric conversion elements, an element isolation area is disposed. The element isolation area electrically and elementally separates the photoelectric conversion elements. The element isolation area is, for example, formed as follows. A grid-like trench (groove) is formed at a semiconductor layer where a plurality of the respective photoelectric conversion elements is formed. The trench surrounds each photoelectric conversion element in a rectangular shape in plan view. An insulating material is embedded in the trench.
The trench for element isolation is generally formed by Reactive Ion Etching (RIE). However, dangling bond may be generated on a surface of the trench formed by RIE. Since an electron caused by dangling bond is generated regardless of existence of incident light, the electron appears as white defect in the captured image, causing image degradation.